Manufacture of alloy pig iron



mu 4%, E92. H. P. PARROCK MANUFACTURE OF ALLOY PIG IRON Filed Dec. 24, 1926 Patented dune 4, 192%.

g T A T E g earner stares.

HARRY P. PARROCK, 0F BBIOQKLINE, MASSACHUSETTS.

MANUFACTURE OF ALLOY PIG- IRON.

Application filed December 24, 1928. Serial No. 156,799.

ore of this character contains approximately one per cent nickel and two per cent chromium. The pig iron resulting from this natural ore contains the alloying metals as they naturally occur and the proportions are not subject to correction in the manner in which it is now produced. Atthe present time no known ores of iron contain all the auxiliary metals now coming into use, such as nickel, chromium, tungsten, vanadium, aluminum, molybdenum and others and no ores contain silicon, phosphorus and manganese in suitable proportions.

In the foundr an alloyin the form of a ferro alloy is added to the molten iron in the ladle. It is also sometimes charged in the stack. Lacking control of the temperature and being pushed for time to allow the alloy to dissolve and because of the loose methods, as much as fifty percent of an alloy is often lost in the slag or on the floor. Furthermore segregation often occurs. These processes lack exactness and bring variable results. One of the advantages of my process is that the waste of alloys in the usual and prevailing method of introducing such alloys in foundry ractice will be reduced if the alloy has alrea y been made in the pig iron.

One of the objects of my invention is to introduce these auxiliary metals into molten iron in an economical manner. A further object is to provide a means for easily correcting the contents of those auxiliary metals already present, such as manganese, silicon,

hosphorous, carbon and sulphur.

Still another object is to provide a practical ,p

method of improving the grey iron foundry trade by increasing the range of useful irons by the use of alloys whileat the same time, the iron maker is to be afforded a means of protecting himself against the loss in time, money and often in reputation arisingf off-iron. By usingmy invention, an appreciable curtailment may be had in the grades of ore carried for mixing purposes with consequent reduction in investment and better regulation of practice.

In carrying out my invention, I use an auxiliary' melting unit comprising an open hearth furnace of suitable design and an electric fur for the manufacture of allo nace. The open hearth furnace may be of the tilting or stationary type and the electric paelting furnace may be of any conventional Referring now to the drawing for a more complete disclosure of the invention, there is shown, by wayof example, a typical lay-out pig iron using hot. metal direct from the b ast furnace.

In this plant 1 is the blast furnace, 2 are hot blast stoves and 3 is the stack therefor.

Adjacent the blast furnace are tracks 4: on which run slag ladles 5 to receive the slag as it comes down the slag runways 6. On the 0pposite side of the blast furnace are tracks 7, leading to a pig casting machine, on which run metal ladles 8 to receive the molten metal as it comes down the metal runways 9 from the blastfurnace or the runway 10 from the open hearth. The main runwayll conduct-s metal 13. Located adjacent the blast furnace 1s the auxiliary melting unit comprising a regenerative open hearth furnace 14: and an electric meltlng furnace 15. An overhead crane ma run on the track 16 for handling ladles an other materials.

The electric furnace is used to premelt the auxiliary or added alloy, preferably in the ferrous form, as ferro-mckel, with a proportion of the iron coming from the blast furnace, to ensure a perfect alloy. That is, if a bath of twenty-five net tons is to be melted in the open hearth furnace to contain one percent nickel when finished, this one percent or five hundred pounds would be melted as, for instance, one thousand pounds of fifty percent ferro-nickel with one I of the molten iron, giving a bath of two thousand pounds in the electric furnace. hen the twenty-five ton heat less one thousand ounds have been brought to the proper temperature on the open hearth bottom, the two thousand pounds of ferro-nickel alloy would be transferred from the electric furnace to the open hearth bath.

The open. hearth furnace would be fired preferably with coke-oven gas; or it could be red by oil, or blast furnace gas, or coal gas. A large electric furnace could be used instead of the open hearth, except that the large caacit would entail urt ermore, the temperature of the arc is not necessary in this operation. A de ree of super-heat above the temperature of t e iron determined by the blast furnace may not into a ladle 12 in the transfer ladle pit thousand pounds much more expense.

' ditions will be regularly delivering No. 2,

- special iron,

,ments are based on the intermediate collecting point,

always be "necessary, since the rich alloy from the electric furnace can be made very hot. But the ability to super-heat the bath of iron is made available by ative feature of the desirable feature in which cools rapidly.

Furthermore if it is desired to remelt cold iron, to reclaim it from off-iron or for any other reason the open hearth furnace, or equal electric, can handle such iron.

y process furnaceenabling it 'to furnish its trade with relatively small proportions of its out-put in without going to the heavy expense of special ores, if available, and of mixed operating. That is, it can furnish a carload sa of fifty tons, out of an otherwise standard ays run of say five hundredtons open hearth furnace-a the case of soft iron which might be made a very soft iron, 3.25-

silicon,w en the ore pile and operating conplain, say 2.00 percent silicon. In like manner it can deliver any commercial alloy in relatively small lots without upsetting the furnace routine.

From the above description it will be seen that I use an open hearth furnace of suitable size and type conveniently placed to take hot metal, with a small furnace for melting alloys.

This melting and alloying unit constitutes an intermediate step between the blast furnace and the pig machine, for that part of the furnace output which can be alloyed to advantage, or which can be corrected for silicon, phosphorus, manganeseand possibly carbon. In carrying out the acid bottom hearth is melting practice inherent in that construction. The action of a basic hearth or of a rammed ore hearth, or of a theoretically neutral hearth is recognized as presenting further phases of the problem, but the limiting conditions do not affect the general principles of my invention. While the use of the present mixer is well established as a means of correcting successive taps by averaging the products and of providing an exercislng a on the process, as in both steel the mixer is not As an auxiliary to regulate pro'.

steady influence plant and foundry practice, a melting or alloying unit.

between furnace and foundry the use of the regener gives a flexibility to the blast complementary electric process as disclosed, an assumed, and state hearth wouldbe melted with the alloy, would make what may Such solution of the alloy, in a relative y lar e bath at high temperature enshres quick an thoroughrsolution of the alloy in the open hearth heat whichin turn may be super-heated above the usual ladle temperature as may be necessary. The resulting alloy iron is of a qua ity which the foundry man cannot reach with the melting unit and general facilities at his disposal. urthermore, the waste in alloys in'ordinary' foundry practice is very high due to spilling, low temperature of thebath, generally the ladle, and the more or less haphazard method of the industry in such matters. In the case of off iron the hearth affords a simple means of correction even for iron that has been stacked in the ards from previous bad runs. In the melting of off irons and its correction, the use of local scrap presents possibilities of lower costs ture.

I claim; I

A method of producing pig-iron to also make alloyed pig iron as required without 7 disturbing the normal operation of the blast furnace comprising smelting the ore in a blast furnace, transferring a portion of the molten iron to an open hearth furnace, heating the molten iron in the open hearth furnace to a high temperature, separately melting a relatively small quantity of alloying metal, and without further treatment of the produced molten iron adding the said alloy to the body of metal in the open hearth furnace, therea ter casting the alloyed pig iron, in the meanwhile casting the undiverted portion of the molten iron from the blast furnace.

In testimony whereof, I have hereunto set my hand at Brookline, Mass, this 20th day of December, 1926.

HARRY P. PARROCK.

be termedthe rich allo of mix-4 

